FRIDAY, March 11, 2016 (HealthDay News) -- Severe migraines are associated with an increased risk of complications during pregnancy and childbirth, especially among older women, new research suggests.

"The results of this study were of particular interest because more than half of the pregnant women with migraine experienced some type of adverse birth outcome, suggesting that these pregnancies should be considered high risk," study author Dr. Matthew Robbins, said in a Montefiore Medical Center news release.

Robbins is director of inpatient services at Montefiore Headache Center. He's also chief of neurology at the Jack D. Weiler Hospital of Montefiore in New York City.

It's important to note that the study only found a link between women with severe migraines and pregnancy and delivery complications. The study wasn't designed to prove that having or treating migraines caused these problems.

The study included 90 women. All of the women sought emergency medical care for severe migraines while pregnant.

About 20 percent of the women had the pregnancy complication preeclampsia, the study found. Women with preeclampsia have dangerously high blood pressure. About 8 percent of women in the general population have this complication, the researchers said.

Nearly 30 percent of the women in the study had preterm delivery. About 10 percent of women in the general population normally have a preterm delivery, according to the study. Nineteen percent of the women with migraines had low-birth weight babies, the study showed. That compares to a rate of 8 percent among women without migraines.

Women aged 35 and older with severe migraines were seven times more likely to have these complications than women in the general population.

Sixty-two percent of the women in the study received a combination of pills and intravenous drugs to treat their migraines. The researchers said it's not clear if these medications played a role in the pregnancy and birth complications.

"These findings need to be replicated with a larger number of women, including those who have migraine that does not manifest with severe attacks during pregnancy," Robbins added.

The study is to be presented in April at the American Academy of Neurology's annual meeting, in Washington, D.C. Findings presented at meetings are generally viewed as preliminary until they've been published in a peer-reviewed journal.